The present invention relates to inking arrangements for use in printing presses, and more particularly to an inking arrangement for printing presses which comprises a fountain roller, a distributing roller and a plurality of vibrating rollers divided axially of the rollers and arranged therebetween, the vibrating rollers being individually switchable back and forth between two positions between the fountain roller and the distributing roller so as to differ in the mode of contact thereof with these two rollers alternately.
For use printing presses, inking arrangements of such type are already known wherein each vibrating roller is rotatably attached to the movable ends of pivotal arms, and the pivotal arms are moved as by pneumatic cylinder or like means to switch the vibrating roller back and forth between a first position where the roller is in contact with the fountain roller and away from the distributing roller and a second position where the roller is in contact with the distributing roller and away from the fountain roller.
However, the conventional inking arrangement described requires pairs of pivotal arms for switching the vibrating rollers between the two positions to result in the problem of necessitating a great installation space.
To solve this problem, an inking arrangement is proposed which comprises a support member in the form of a rectangular pipe and disposed in parallel to a fountain roller and a distributing roller, a plurality of short cylindrical movable members fitted around the support member, each of the movable members being formed with a rectangular bore having the support member inserted therethrough with a clearance provided in the direction of one width of the support member, vibrating rollers rotatably mounted on the respective movable members externally thereof, and change-over devices provided on the support member and positioned between the support member and the respective movable members for moving the movable member in the above-mentioned direction of width of the support member, each by an electromagnet and a spring, to switch the vibrating rollers individually between different positions. (see JP-A No. 38160/1985).
With this arrangement, the position of the movable member is changed by energizing or deenergizing the coil of the electromagnet of the change-over device. When the coil of the electromagnet is not energized, the movable member is located in the first position by the biasing force of the spring, while when the coil is energized, the movable member is shifted to the second position by the magnetic drive force of the electromagnet.
The arrangement nevertheless has a problem attributable to the generation of heat of the electromagnet of the change-over device as will be described below. The spring has a considerably great biasing force since the spring moves a considerably great portion comprising the movable member and the vibrating roller to press the vibrating roller into contact with the fountain roller or distributing roller. A great magnetic drive force is required of the electromagnet because the electromagnet is adapted to press the vibrating roller into contact with the distributing roller or fountain roller by moving the great portion against the biasing force of the spring. Accordingly, a sufficient drive force is not available unless the electromagnet is large-sized, and an increase in the size of the electromagnet makes the change-over device greater in size. Although the coil of the electromagnet generates a large quantity of heat, the electromagnet is disposed in the support member inside the bore of the movable member and is therefore unable to dissipate the heat, greatly raising the temperature of the electromagnet and the support member. This entails the likelihood that the coil of the electromagnet will be thermally damaged, or the support member will expand thermally, no longer permitting the movable member to move smoothly relative to the support member. It is necessary to provide a cooling device to preclude this drawback, whereas the change-over device then becomes complex in construction and greater in size.
Accordingly, the foregoing publication proposes an arrangement which comprises a plurality of movable members each in the form of a short hollow cylinder and fitted around a support member in the form of a round tube so as to be movable along one diametrical direction of the support member, and a change-over device comprising a cylinder provided inside the support member and having a piston in the cylinder portion, and a spring. The movable members are movable along the diametrical direction of the support member, each by the piston and the spring, to switch the vibration rollers individually between different positions.
With this arrangement, the movable member is switched between the different positions by controlling the supply of air to the cylinder portion of the change-over device with a switching valve. When no air is supplied to the cylinder portion, the movable member is switched to the first of the positions by the biasing force of the spring, while when air is supplied to the cylinder portion, the movable member is switched to the second of the positions by the biasing force of the piston.
As will be described below, however, this arrangement has the problem that the change-over device is composed of a large number of parts, difficult to assemble and cumbersome to maintain, requires a large installation space, great air consumption and a prolonged response time in changing the position of the vibration roller. Stated more specifically, aside from the support member, each ink transfer roller requires one cylinder, and also piping between the cylinder and each switching valve and piping between each switching valve and a compressed air source, hence an increased number of parts. Also required are work for mounting the cylinders in the interior of the support member, work for piping between each cylinder and each switching valve, work for the piping between the switching valve and the compressed air source, difficult assembling work and cumbersome maintenance work. The switching valves are arranged externally of the support member since it is impossible to provide the valves inside the support member which has in its interior the cylinders and the piping between the compressed air source and the cylinders. Accordingly there is a need to provide a large space for the installation of the switching valves externally of the ink transfer rollers. This requires elongated piping between the cylinders provided inside the support member and the switching valves arranged outside the support member, consequently necessitating greatly increased air consumption when air is supplied to each cylinder portion and an increased period of time until the piston actually moves the movable member after the switching valve is controlled, i.e., a prolonged response time in changing the position of the ink transfer roller. Further because the distance between the cylinder and the switching valve generally differs from cylinder to cylinder, the length of the piping differs from cylinder to cylinder if the piping is installed in the usual manner, with the result that the response time in changing the position of the ink transfer roller varies from roller to roller. To avoid this, the pipes between the cylinders and the respective switching valves need to have equal lengths, whereas it is then necessary to give each pipe the same length as the longest pipe to entail a need for correspondingly excessive piping and additional installation space.
Accordingly, we have proposed an inking arrangement which comprises a support member in the form of a prism, movable members each having a groove extending over the entire length thereof and formed in a surface thereof slidable in contact with the support member and defining a rectangular bore, and switching valves each positioned in the groove and mounted on the support member on the surface thereof facing the groove of the movable member, the support member being bored to provide cylinder portions, the support member being internally formed with a common air supply channel extending through the support member axially thereof and communicating at one end thereof with a compression air supply source, a plurality of communication passageways each holding the air supply channel in communication with the switching valve, and a plurality of communication passageways each holding the switching valve in communication with the cylinder portion (see JP-A No. 71863/1994).
The support member and the switching valve need to be provided inwardly of the outer periphery of the movable member in the case of this arrangement, whereas since the support member only is present with respect to the direction of movement of the movable member, the support member can be given an increased width in this direction. However, the support member and the switching valve are present with respect to a direction orthogonal to this direction, so that the width of the support member can not be increased in the second-mentioned direction. This gives diminished flexural rigidity to the support member in its entirety, failing to press the ink vibrating roller into contact with the fountain roller or distributing roller with a great pressure.
An object of the present invention is to overcome the foregoing problems and to provide an inking arrangement for printing presses comprising a change-over device which is reduced in installation space, diminished in the number of components, easy to assemble and maintain, decreased in air consumption, shortened in response time in changing the position of the vibrating roller and capable of giving increased flexural rigidity to the support member.
The present invention provides an inking arrangement for printing presses which comprises a fountain roller and a distributing roller supported by a frame so as to be parallel to each other, and a plurality of vibrating rollers divided axially of these rollers and arranged at an interval axially thereof between the rollers, the vibrating rollers being individually switchable between two positions between the fountain roller and the distributing roller so as to differ in the mode of contact thereof with the rollers, the inking arrangement further comprising a support member in the form of a prism and secured to the frame so as to be parallel to the fountain roller and the distributing roller, a plurality of short cylindrical movable members fitted around the support member, each of the movable members being formed with a rectangular bore having the support member inserted therethrough with a clearance provided in the bore in the direction of one width of the support member, the vibrating rollers being rotatably mounted on the respective movable members externally thereof, and change-over devices provided on the support member and positioned between the support member and the respective movable members for moving the respective movable members along said direction of width of the support member to switch the vibrating rollers individually between said positions, each of the change-over devices comprising a piston slidably inserted in a cylinder portion for pneumatically biasing the movable member toward one side in said width direction, a spring for biasing the movable member toward the other side in said width direction, and a switching valve having an inlet port, an outlet port and an exhaust port communicating with a compressed air source, the cylinder portion and the atmosphere respectively for controlling supply of air to the cylinder portion when changed in the energization state thereof, the movable member being switchable to said one side in the width direction by the biasing force of the piston when air is supplied to the cylinder portion, the movable member being switchable to said other side in the width direction by the biasing force of the spring when no air is supplied to the cylinder portion, the inking arrangement being characterized in that each of the movable members has a groove extending over the entire length thereof and formed in a surface thereof slidable in contact with the support member and defining the rectangular bore, the support member having a groove formed in a surface thereof opposed to the groove of the movable member, the switching valve being positioned in the grooves and mounted on the support member on a bottom surface defining its groove and facing the groove of the movable member, the support member being bored to provide the cylinder portion, the support member being internally formed with a common air supply channel extending through the support member axially thereof and communicating at one end thereof with the compression air supply source, a plurality of communication passageways each holding the air supply channel in communication with the inlet port of the switching valve, and a plurality of communication passageways each holding the outlet port of the switching valve in communication with the cylinder portion.
Thus, each of the movable members has a groove extending over the entire length thereof and formed in a surface thereof slidable in contact with the support member and defining the rectangular bore, the support member has a groove formed in a surface thereof opposed to the groove of the movable member, and the switching valve is positioned in the grooves and mounted on the support member on a bottom surface defining its groove and facing the groove of the movable member. Accordingly, the electric wires for each switching valve can be passed through the grooves to extend to the outside. Further the support member in the form of prism is internally formed with a common air supply channel communicating with the compression air supply source, a plurality of communication passageways each holding the air supply channel in communication with the inlet port of the switching valve, and a plurality of communication passageways each holding the outlet port of the switching valve in communication with the cylinder portion. Accordingly, the air supply channel formed in the support member needs only to communicate at its one end with the compressed air source. Except for the wiring for the switching valves and the piping between the air supply channel of the support member and the air source, the change-over devices are arranged predominantly inside the ink transfer rollers. This eliminates the need for a great space for installing the change-over devices externally of the ink transfer rollers, rendering the devices installable in a reduced space.
The support member in the form of a prism is bored to provide each cylinder portion. This obviates the need to provide a cylinder separately. The piping needed is only between the air supply channel of the support member and the compressed air source as described above, while there is no need for the piping between each cylinder portion and each switching valve, and there is little or no need for the piping between the switching valve and the compressed air source. Consequently, the change-over device is much smaller than in the prior art in the number of components. There is no need for the work for installing cylinders in the support member, work for piping between each cylinder portion and the corresponding switching valve, and work for piping between the switching valves and the air source. The change-over device is therefore easy to assemble and maintain.
The support member is provided, at the portion thereof where each ink transfer roller is positioned, with the switching valve for the transfer roller and also with the cylinder portion and the passageway holding the outlet port of the valve in communication with the cylinder portion. This greatly shortens the length of the passageway communicating with the cylinder portion. The passageways communicating with the respective cylinder portions and provided for the respective ink transfer rollers can all be made to have equal lengths. The reduction in the length of the passageways leading to the cylinder portions results in decreased air consumption when air is supplied to the cylinder portions and shortens the response time involved in changing the position of the ink transfer rollers. The passageways communicating with the cylinder portions and all made equal in length obviate the likelihood that the response time in changing the position of the ink transfer roller will vary from roller to roller.
Not only each of the movable members has a groove extending over the entire length thereof and formed in a surface thereof slidable in contact with the support member and defining the rectangular bore, but the support member also has a groove formed in a surface thereof opposed to the groove of the movable member, and the switching valve is positioned in the grooves and mounted on the support member on a bottom surface defining its groove and facing the groove of the movable member. Accordingly, in a direction orthogonal to the direction of movement of the movable member, the support member is given a width which is increased by an amount corresponding to the wall portions at opposite sides of the support member groove. The support member can therefore be enhanced in flexural rigidity in its entirely, permitting the vibrating roller to be pressed into contact with the fountain roller and the distributing roller with an increased pressure.
The exhaust port of each switching valve may be left opened as it is to the atmosphere, or made to communicate with the atmosphere by way of the passageway formed in the support member.
For example, the cylinder portion is formed by boring the support member in a surface thereof toward said one side in said width direction and has the piston slidably inserted therein, the piston being projectable from the support member to bias the movable member toward said one side in said width direction when air is supplied to the cylinder portion, the support member being formed with a spring cavity in a surface thereof toward said other side in said width direction, the cavity having a biasing member slidably inserted therein and having inserted therein the spring for causing the biasing member to bias the movable member toward said other side in said width direction.
The cylinder portion and the spring cavity are then easy to form, and the support member is simplified in the structure providing the cylinder portion and the piston and also in the structure providing the biasing member. The piston, the spring and the biasing member are also easy to install in the support member.
Useful as the biasing member is, for example, a ball, pin or the like.
For example in this case, each movable member is formed with a recess in a surface thereof defining the rectangular bore and opposed to the piston and a recess in a surface thereof defining the rectangular bore and opposed to the biasing member, the movable member being positioned in place relative to the support member axially thereof by the piston partly fitting in the recess opposed thereto and by the biasing member partly fitting in the recess opposed thereto.
When the movable members are thus positioned in place relative to the support member axially thereof, each pair of adjacent movable members, as well as each pair of adjacent vibrating rollers, can be axially spaced apart by a suitable clearance to render these rollers smoothly movable relative to each other. Further since the movable member can be positioned in place by the piston and the biasing member for use in switching the position of the movable member, there is no need to use additional parts for positioning the movable member, hence a reduced number of components.
For example in this case, a projection can be formed on the end face of the piston and fitted in the corresponding recess to cause the piston end face around the projection to be pressed against the bore-defining surface of the movable member around this recess. The biasing member, when in the form of a pin, can be similarly constructed. Alternatively, the piston or the biasing member may be tapered at its outer end so that the tapered end is fitted in the recess. When the biasing member is a ball, the outer periphery of the ball is made partly fittable in the recess.
For example in this case, the support member can be internally formed with a passageway for holding the exhaust port of each switching valve in communication with the spring cavity to cause the exhaust port to communicate with the atmosphere through the passageway and the spring cavity.
For example, the communication passageway holding the outlet port of the switching valve in communication with the cylinder portion is formed at a junction thereof with the cylinder portion with a flaring part diametrically enlarged toward the cylinder portion.
The flaring part then diminishes the resistance to the flow of air through the junction between the cylinder portion and the communication passageway, permitting air to flow smoothly from the passageway into the cylinder portion and also from the cylinder portion into the passageway and shortening the response time involved in the pneumatic movement of the piston to result in a shortened response time in switching the position of the ink transfer roller.
For example, a dustproof member in the form of a cylinder and made of a rubberlike elastic material is fitted around end portions of each pair of adjacent movable members to interconnect the end portions.
The dustproof member then precludes ink, dust or the like from ingressing into the interior of the movable members. The dustproof member, which is made of rubberlike elastic material, elastically deforms when the adjacent movable members move individually to absorb the movement, consequently allowing the movable members to move individually to switch the vibrating rollers individually between the two positions.
For example in this case, inward flange portions formed at opposite ends of the dustproof member are fitted in respective annular grooves formed in the outer peripheral surfaces of the movable members, whereby the dustproof member can be fixed to the movable members. The dustproof member can be secured to the outer peripheral surfaces of the movable members alternatively as by adhering its opposite ends thereto.